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In situ AFM observations show that when PILP droplets contact a surface, their initial properties are either a liquid with a high interfacial tension (350 mJ m -2 ) or a soft gel-like material with a low modulus (less than 0.2 MPa). These findings suggest that PILP may initially be liquid-like to infiltrate collagen fibrils, enabling the production of interpenetrating composites, and/or become viscoelastic, to provide a means for moulding minerals.

A long-standing challenge in the mining industry is the separation of mineral particles that have similar surface characteristics for which surfactant-based flotation collectors cannot discriminate. In Florida phosphate mining, this problem occurs in the separation of dolomite [CaMg(CO 3 ) 2 ] contaminants from the desired francolite mineral {a fluorapatite [Ca 5 (PO 4 ) 3 (F,OH)]}. In this study, phage display techniques were used to select phage clones with specific binding affinity to francolite, which were then tested in a benchtop bubbler flotation apparatus for their ability to selectively float francolite particles from mixtures containing dolomite. Contact angles measured with the captive bubble technique were used to examine changes in the surface character of the mineral particles upon adsorption of the phage, which showed that the most selective phage led to an increase in the contact angle from 16 to 50°. Although this is below the level considered hydrophobic, the correlation between contact angles and increased flotation recovery suggests that the phage coat proteins are behaving as efficient bioamphiphiles for the attachment of the particles to air bubbles, demonstrating a new and environmentally friendly type of biocollector system. The chemical and physical characteristics of the phage "tail" peptides were evaluated to offer an explanation for the specificity of phage binding. We conclude with a discussion of the potential benefits of this biotechnology approach, even for commodity industries such as mining or other particle separation systems, when costs and sustainability are considered.

With the aging population, there is a growing need for mineralized tissue restoration and synthetic bone substitutes. Previous studies have shown that a polymer-induced liquid-precursor (PILP) process can successfully mineralize collagen substrates to achieve compositions found in native bone and dentin. This process also leads to intrafibrillar apatitic crystals with their [001] axes aligned roughly parallel to the long axis of the collagen fibril, emulating the nanostructural organization found in native bone and dentin. When demineralized bovine bone was remineralized via the PILP process using osteopontin (OPN), the samples were able to activate mouse marrow-derived osteoclasts to similar levels to those of native bone, suggesting a means for fabricating bioactive bone substitutes that could trigger remodeling through the native bone multicellular unit (BMU). In order to determine if OPN derived from bovine milk could be a cost-effective process-directing agent, the mineralization of type I collagen scaffolds using this protein was compared to the benchmark polypeptide of polyaspartic acid (sodium salt; pAsp). In this set of experiments, we found that OPN led to much faster and more uniform mineralization when compared with pAsp, making it a cheaper and commercially attractive alternative for mineralized tissue restorations.